The present invention relates to a resin composition for molding, which comprises a saponified copolymer of ethylene and vinyl acetate, and a polyamide resin.
Since the composition comprising a saponified copolymer of ethylene and vinyl acetate, and a polyamide has useful properties of oxygen gas-barrier, oil-resistance and solvent-resistance due to the saponified copolymer and in addition, impact-resistance due to the polyamide, the melt-molded articles of the composition are used in various purposes including films, sheets and containers for packaging foodstuffs.
In literatures, for instance, molded articles comprising a saponified copolymer of ethylene and vinyl acetate, and nylon 6 or nylon 66 is disclosed in Japanese Patent Publication No. 44-24277 (1969).
However, in the case of carrying out the melt-molding of the above-mentioned resin composition for a long time, gel is generated in the molten resin, and/or dregs of the resin are accumulated in the screw part and the outlet of the extruder resulting in the damage of the physical properties of the molded articles or in the discontinuance of the molding operation due to the clogging of the screen and the nozzle of the extruder. In such a case, it is inevitable to take the extruder to pieces for removing the adhered dregs, and such an additional operation has a tendency of impairing the long-run processability in view of the efficiency of molding operation.
Although, in order to solve the above-mentioned demerit, a method of improving the long-run property by using a modified polyamide through copolymerization has been proposed in Japanese Patent Applications Laying-Open (KOKAI) No. 54-78749 (1979) and No. 54-78750 (1979), the continuous melt-molding operation of only several tens of hours becomes possible by the method thereof.
Obviously, in industrial scale operations, the longer a continuous melt-molding operation can be conducted, the more profitable the operation becomes.
As a result of the present inventors' studies for solving the above-mentioned problem, it has been found that a resin composition comprising (1) a saponified copolymer of ethylene and vinyl acetate, and (2) a polyamide resin which fulfills the following formula: ##EQU2## wherein (A) is the number of terminal carboxyl groups (--COOH) and (B) is the number of terminal groups represented by the formula: --CONRR' wherein R is a hydrocarbyl group having 1 to 22 carbon atoms and R' is a hydrogen atom or a hydrocarbyl group haivng 1 to 22 carbon atoms, has excellent long-run processability characteristics during melt-molding, and because of this excellent long-run processability feature, problems are avoided such as gel formation and the adherence of dregs with the result that molded articles of excellent physical properties can be continuously produced.